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-rw-r--r--drivers/base/dd.c47
1 files changed, 19 insertions, 28 deletions
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 06051767393..e4ffbcf2f51 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -52,6 +52,7 @@ static DEFINE_MUTEX(deferred_probe_mutex);
static LIST_HEAD(deferred_probe_pending_list);
static LIST_HEAD(deferred_probe_active_list);
static struct workqueue_struct *deferred_wq;
+static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
/**
* deferred_probe_work_func() - Retry probing devices in the active list.
@@ -135,6 +136,17 @@ static bool driver_deferred_probe_enable = false;
* This functions moves all devices from the pending list to the active
* list and schedules the deferred probe workqueue to process them. It
* should be called anytime a driver is successfully bound to a device.
+ *
+ * Note, there is a race condition in multi-threaded probe. In the case where
+ * more than one device is probing at the same time, it is possible for one
+ * probe to complete successfully while another is about to defer. If the second
+ * depends on the first, then it will get put on the pending list after the
+ * trigger event has already occured and will be stuck there.
+ *
+ * The atomic 'deferred_trigger_count' is used to determine if a successful
+ * trigger has occurred in the midst of probing a driver. If the trigger count
+ * changes in the midst of a probe, then deferred processing should be triggered
+ * again.
*/
static void driver_deferred_probe_trigger(void)
{
@@ -147,6 +159,7 @@ static void driver_deferred_probe_trigger(void)
* into the active list so they can be retried by the workqueue
*/
mutex_lock(&deferred_probe_mutex);
+ atomic_inc(&deferred_trigger_count);
list_splice_tail_init(&deferred_probe_pending_list,
&deferred_probe_active_list);
mutex_unlock(&deferred_probe_mutex);
@@ -187,8 +200,8 @@ static void driver_bound(struct device *dev)
return;
}
- pr_debug("driver: '%s': %s: bound to device '%s'\n", dev_name(dev),
- __func__, dev->driver->name);
+ pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
+ __func__, dev_name(dev));
klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
@@ -265,6 +278,7 @@ static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
static int really_probe(struct device *dev, struct device_driver *drv)
{
int ret = 0;
+ int local_trigger_count = atomic_read(&deferred_trigger_count);
atomic_inc(&probe_count);
pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
@@ -310,6 +324,9 @@ probe_failed:
/* Driver requested deferred probing */
dev_info(dev, "Driver %s requests probe deferral\n", drv->name);
driver_deferred_probe_add(dev);
+ /* Did a trigger occur while probing? Need to re-trigger if yes */
+ if (local_trigger_count != atomic_read(&deferred_trigger_count))
+ driver_deferred_probe_trigger();
} else if (ret != -ENODEV && ret != -ENXIO) {
/* driver matched but the probe failed */
printk(KERN_WARNING
@@ -570,29 +587,3 @@ void driver_detach(struct device_driver *drv)
put_device(dev);
}
}
-
-/*
- * These exports can't be _GPL due to .h files using this within them, and it
- * might break something that was previously working...
- */
-void *dev_get_drvdata(const struct device *dev)
-{
- if (dev && dev->p)
- return dev->p->driver_data;
- return NULL;
-}
-EXPORT_SYMBOL(dev_get_drvdata);
-
-int dev_set_drvdata(struct device *dev, void *data)
-{
- int error;
-
- if (!dev->p) {
- error = device_private_init(dev);
- if (error)
- return error;
- }
- dev->p->driver_data = data;
- return 0;
-}
-EXPORT_SYMBOL(dev_set_drvdata);